A Quantum Internet Connected By Cargo Ships Is Not As Crazy As It Sounds

Our internet has a physical infrastructure: thousands of kilometres of cables that criss-cross the oceans. The quantum internet, when it exists, will have a physical infrastructure too. But you can't send quantum bits, or "qubits", on fibre optic cables, so a group of physicists has proposed a bizarre solution: cargo ships carrying data on diamond-based drives. And it's not a completely whacky idea.

There are myriad reasons we do not yet have a quantum internet, but one of them is that we can't send quantum information over long distances. City-wide networks are being built, but they only cover distances of 160km or less.

To build larger quantum networks, we'll need devices called quantum repeaters to boost the signal. But those things are tricky to build. For one, as Tech Review notes, they have to be kept close to absolute zero. Good luck building a super-fridge at the bottom of the Pacific Ocean.

Instead, a group of physicists argue we should take a page from the sneakernet, aka transferring data on physical disks and drives. Massive container ships could cross our oceans carrying diamond-based hard drives, which are especially stable. Shipping might seem agonisingly slow for everyone used to instant videos, but the quantum internet will also be completely secure due to the laws of physics. Anyways, cargo ships are huge. A ship carrying 10,000 containers worth of quantum bits that crosses the ocean between Japan and the US would still come out to a data transfer of up to 1TB per second.

Obviously, this is all a theoretical exercise, but it highlights a legitimate and important problem for the quantum internet. The internet, quantum or not, isn't just information magically appearing on our screens but physical structures that have to be designed, built and maintained. [Tech Review]